1. Field of the Invention
This invention relates to a method for driving a surface discharge and matrix type of plasma display panel (also designated as a PDP hereinafter).
2. Description of Related Art
The plasma display panel is well known as one of thin two-dimensional displays, and various researches and studies have recently been conducted on the plasma display panels. An AC discharge and matrix type of plasma display panel having a memory function is well known as one of such plasma display panels. FIG. 1 shows a schematic diagram of a plasma display apparatus including a plasma display panel.
Referring to FIG. 1, a driving apparatus 100 receives video signals and converts a set of the received video signals every one pixel to digital pixel data. The driving apparatus 100 then generates pixel data pulses corresponding to the pixel data to apply the pixel data pulses to column electrodes Dl to Dm in the plasma display panel 11. The PDP 11 comprises the column electrodes D1 to Dm, and row electrodes X1 to Xn and Y1 to Yn extending perpendicularly to the column electrodes, in which two adjacent ones of the row electrodes Xi and Yi are paired to one another to form a row of the display on the display panel. The PDP further includes a dielectric layer formed between the column and row electrodes. A cross section in which a pair of row electrodes and a column electrode are crossed to each other constitutes a single pixel cell.
The driving apparatus 100 produces priming pulses PPx and PPy for all of the row electrodes in the PDP 11 and then applies the pulses PPx and PPy to the respective row electrodes X1 to Xn, and Y1 to Yn to forcibly cause a discharge between a pair of row electrodes Xi and Yi for generating (or destroying) a wall charge within the pixel cell. The driving apparatus 100 also generates a scan pulse SP for writing the pixel data in the PDP 11, and discharge-sustaining pulses IPx and IPy for sustaining a discharge emission, an erasing pulse EP for ceasing a sustained discharge emission, thereby applying these pulses to the row electrodes X1 to Xn, and Y1 to Yn in the PDP 11.
FIGS. 2A to 2E show the timing charts for applying the above various types of driving pulses to the various electrodes to illustrate the suggested method for driving the PDP.
Referring to FIGS. 2A to 2E, the driving apparatus 100 supplies all of the row electrodes X1 to Xn with the priming pulses PPx which have a negative potential, and simultaneously supplies all of the row electrodes Y1 to Yn with the priming pulses PPy which have a positive potential. The application of the priming pulses causes discharges between the pair of row electrodes in all of the pixel cells of the PDP 11. The discharge produces charged particles in each of the pixel cells. After the disappearance of the discharge, the wall charge remains in the dielectric layer (simultaneous resetting step). The priming pulses PPx, PPy with a long time constant are used for suppressing the discharge emission non-related to the displaying due to themselves to improve the contrast.
The driving apparatus 100 then applies pixel-data pulses DP1 to DPn corresponding to pixel data at every row to the column electrodes D1 to Dm in turn. In this case, these pixel data pulses DP1 imply pulses of the number of "m" corresponding to pixel data for ranging from the first column to the m-th column in the first row. The pixel data pulses DP2 imply pulses of the number of "m" corresponding to pixel data for ranging from the first column to the m-th column in the first second row.
The pixel data pulses corresponding to pixel data for the "m" pieces in number are applied to the column electrodes D1 to Dm at the same time respectively. For example, for the column electrodes to have contents of the pixel data equal to a logical value "0", the positive voltage pixel data pulses are applied to such column electrodes. On the other hand, for the column electrodes to have contents of the pixel data equal to a logical value "1", no voltage pixel data pulses is applied to such column electrodes. The driving apparatus 100 generates the scan pulse SP and applies them in turn to the row electrodes Y1 to Yn with the timing for applying the pixel data pulses DP1 to DPn to the column electrodes thereby to perform to write the pixel data to every row (addressing period or step).
In the addressing period, the pixel cells each having a column electrode D to which the scan pulse SP and the positive voltage pixel data pulse may be applied at the same time are discharged and excited, so that most of the wall charges which has been generated by simultaneous resetting step disappears. As a result, in the period (B) appearing in FIGS. 2A to 2E respectively, a very small amount of the positive wall charges remains at the side of the row electrodes Y and, a very small amount of the negative voltage wall charges remains at the side of the column electrodes D as shown in FIG. 3B.
On the contrary, the wall charges which have been generated by simultaneous resetting step charges may remain at the row electrodes as they are as shown in FIG. 4B even in the addressing period for writing the pixel data pulses, when only the scan pulses SP are applied to the row electrodes but any pixel data pulse is not applied to the column electrodes so that no discharge occurs at the pixels.
Next, The driving apparatus 100 then repeatedly applies a series of discharge-sustaining pulses IPx, each of which has a positive voltage, to the row electrodes X1 to Xn, and also repeatedly applies a series of other discharge-sustaining pulses IPy, each of which has a positive voltage, to the row electrodes Y1 to Yn at offset timings from those of the former discharge-sustaining pulses IPx. The only pixel cells which hold the wall charge maintain the discharge emissions (sustained discharge period).
In this case, the only pixel cells which hold many wall charges maintain the discharge emissions every time the discharge-sustaining pulses IPx and IPy are applied thereto in the period (B) appearing in FIGS. 2A to 2E. In other words, the state of the wall charges shown in FIG. 4B is kept during the period (C) appearing in FIGS. 2A to 2E as shown in FIG. 4C, so that the pixel cells perform the discharge and emit light whenever the discharge-sustaining pulses IPx and IPy are applied thereto.
On the other hand, the pixel cells which hold the state of the wall charges shown in FIG. 3B do not discharge because of a very small amount of the wall charges. The state of the wall charges shown in FIG. 3B is kept as it is, as shown in FIG. 3C.
In the method for driving a surface discharge and matrix type of PDP, a one cycle for displaying an image consists of the simultaneous resetting step, the addressing step, the sustained discharge step is repeated. Therefore, after the sustained discharge period is ended, the simultaneous resetting step is started again. At the time the sustained discharge period is just ended, there are some pixel cells lightened by the sustained discharge and the other pixel cells darkened due to non-sustained discharge respective having the states of the wall charges shown in FIGS. 3C and 4C respectively. Accordingly, there are different states of the wall charges even after the simultaneous resetting step for forming the wall.
The different states of the wall charges in the pixel cells constructing the display panel causes the addressing step unstable in operation to disturb the accurate displaying of the image.